The improvement of the bearing and deformation behaviour by means of a geosynthetic reinforcement placed at the base of a layer of granular fill on the surface of soft clay ( called reinforced two-layer system) is examined. Therefore site tests (scale 1:1) have been performed with variations in the manner of the applied geosynthetics (wovens, non-wovens and geogrids) and the thicknesses of the granular fill The tests were performed until reaching the bearing capacity of the systems. For the reinforced systems increases between 52 % and 108 %, compared to the unreinforced system, were obtained. Subsequently nonlinearelastic-viscoplastic calculations, based on the Finite Element Method (FEM), were performed to evaluate the quality of the received prognoses by comparison with the results of the site tests. Using material parameters exclusively from laboratory tests (no back-calculation analysis) a very good accordance of the FEM calculations with the site tests could be established.